The present invention relates to speed change control units for bicycles.
In particular, the invention relates to a speed change control unit of the type comprising a rotor, carrying a pulley for winding a change control cable, said rotor being rotatably mounted within a body supporting a bicycle brake lever and being provided with indexing means defining the operative positions of the rotor corresponding to the various transmission ratios which can be selected by the speed change device, said unit further comprising two rotor driving levers located at positions which can be easily reached by the fingers of the hand of the cyclist without substantially modifying the position of the hand on the bicycle handlebar, said levers being adapted to cause rotation of the rotor in the two opposite directions respectively, with the aid of associated ratchet-like means. A unit of this type has been manufactured and marketed by the Applicant for many years under the trademark "ERGOPOWER" and has formed the subject of U.S. Pat. No. 5,479,776, as well as parallel German patent No. 44 13 610 and French patent No. 2.704.199.
In recent years, the use has become more and more popular in bicycles of on-board computers with an associated display for enabling the cyclist to display various operative parameters, including also the transmission ratio which is selected by means of the speed change device. Therefore, it has become necessary to provide transducer devices able to send electrical signals indicative of the operative conditions of the speed change device to an electronic control unit.